I'm with you on Curation Guilds. That's been on the waiting list for far too long... If I were to pick 3 things I would say

1. Guilds
2. Something to empower manual voters. Users competing with bots by becoming like bots is a real turnoff for me right now (note vote:view ratio)
3. Some incentives for curating new authors instead of always the same.

There are also lots of frontend features I'd like to see like About pages for users to link their best posts, a feed that shows what users are voting for, a checkbox for resteems, and PERKS! I would love to have some perks that you have to work your way up to by powering up.

Edit: I want to add

4. SMART VOTES

I hope we can finally have an upvote downvote system that ends the social stigma attached to the flag.